It is probably not even important anymore by now (as he already bought the knife, I guess) but maybe some other guys have the same question and will read this
so the hell with it, here are my 2 cents:
Get the large! I handled both the small and the large for a while. The small is neat. But If it's in your pocket, you want to know IT'S THERE! The small one just disappears, IMO. The other thing is: People ask all the time "what did you pay".
I know it sounds weird
but if someone would say YOU PAID 330 DOLLARS FOR A SMALL SEB?!?! I would go "hehe
wellllll *break out in sweat*".
But if someone says YOU PAID 400 DOLLARS FOR A LARGE SEB?!?!? I would say "FUCK YEAH!"
(To be honest, here in Germany, with tax and customs and everything, you pay even 650$)
Long story short: For that amount of money
you want to have something in hand. With the large, you do!
The office factor: I work in an office too. On top of that, one-hand knifes are illegal here. So is a small knife better? NO! So are co-workers scared? Maybe.
But once they understand that you are a knife guy, they will see things differently.
Just infect them with your passion. Make them understand what's so great about knifes. And after 2-3 times they see you handle with that thing, they don't even care anymore.
I flip my balisong all day at work. No one even looks anymore. (i hope it's the non-caring part. And not that they're scared shitless)